1. Technological Field
The present invention relates to a green compact electrode for discharge surface treatment and a method of manufacturing the green compact electrode for discharge surface treatment and more particularly, to a green compact electrode (discharge electrode) used for discharge surface treatment to form hard anodic oxidation coatings on a work surface as well as to a method of manufacturing the green compact electrode.
2. Background Technology
Disclosed in Japanese Patent Laid-Open Publication No. HEI 9-19829 is a method of discharge surface treatment that uses a green compact electrode in the presence of a treatment liquid such as discharge treatment oil, and uses a pulse discharge between a green compact electrode and a work to form a hard anodic coating of the material of the electrode or of a substance such as metal carbide of TiC or so yielded through reaction of the electrode material on the work surface by the discharge energy.
Generally, the green compact electrode is prepared by making use of a property of the metal powder that the powder hardens when a powder of metal such as Ti is filled in a die and the metal powder in the die is pressured and compacted by a pressure punch.
The green compact electrode does not undergo sintering even when the metal powder is used, which is different from the electrode for discharge processing disclosed in Japanese Patent Laid-Open Publication No. SHO 56-126535 and Japanese Patent Laid-Open Publication No. SHO 62-127448, therefore, the electrode strength and the electric resistance finally achieved are decided depending on a state when its pressure and compacting are completed.
Therefore, in order to obtain a required final electrode strength and electric resistance, the green compact electrode requires the pressure of about 5 tonf/cm2 as the compacting pressure. If the compacting pressure is lower than this, the strength of the compacted electrode may not be sufficient or the electric resistance of the electrode may become extremely large, so that the electrode can not appropriately be used as a green compact electrode for discharge surface treatment.
On the other hand, however, when an electrode is compacted with such the large compacting pressure, the pressure to the metallic die is also larger, and for this reason the green compact electrode may be chipped or broken when the green compact electrode is being taken out of the metallic die after being compacted, so that manufacture yields of the green compact electrode are resultantly low.
As described above, the requirement of a large compacting pressure for pressuring and compacting a green compact electrode for discharge surface treatment is largely caused by the facts that a linkage structure of particles can be loose only with particles of metal carbide such as TiC, and that powder can not uniformly be filled in a metallic die. The technology using a submerged discharge phenomenon has been disclosed in Japanese Patent Laid-Open Publication No. Hei. 7-197275. There has been disclosed in Japanese Patent Laid-Open Publication No. Hei. 7-197275 compression and compaction as a method of manufacturing a green compact electrode. However, with only the compression and compaction pressure distribution easily becomes non-uniform, and especially, when the size of the electrode is large it is difficult to maintain a high-quality.
The present invention has been made for solving the problems described above, and it is an object of the present invention to provide a green compact electrode for discharge surface treatment which has required electrode strength and electric resistance value as a green compact electrode for discharge surface treatment through compacting with a comparatively smaller compacting pressure and which can obtain high manufacture yields, and a method of manufacturing the green compact electrode for discharge surface treatment.
The present invention can provide a green compact electrode for discharge surface treatment used for discharge surface treatment for generating discharge between a work and a green compact electrode obtained by pressuring and compacting a metal powder or a powder of a compound metal, and by using the discharge energy forming a coating consisting of an electrode material or a substance obtained through reaction of the electrode material with the discharge energy on the work surface; the electrode is obtained by mixing soft metal powder with a metal powder or a powder of a compound metal, and pressuring and compacting the mixed powder.
Accordingly, when a green compact electrode is pressured and compacted, the soft metal powder enters in the inter-particle space of the metal powder or compound metal powder as a bonding agent and plastically forms in the inter-particle space to harden the electrode with powder, which makes the electric resistance of the electrode lower. With this feature, the electrode strength and electric resistance required as a green compact electrode for discharge surface treatment can be obtained even though the electrode is compacted at a low compacting pressure.
The present invention can provide a green compact electrode for discharge surface treatment in which the compound metal powder is a powder of TiH2 and the soft metal powder is a powder of Ag.
Accordingly, when a green compact electrode is pressured and compacted, the Ag powder which is comparatively soft and has low electric resistance enters the inter TiH2-particle space, plastically deforms in the inter-particle space and harden the electrode with powder, which makes the electric resistance of the electrode lower. With this feature, the electrode strength and electric resistance required as a green compact electrode for discharge surface treatment can be obtained even though the electrode is compacted at a low compacting pressure. In this green compact electrode, hard anodic oxidation coating of TiC is obtained in the discharge surface treatment due to a reaction of TiH2 with the carbon in the treatment liquid.
The present invention can provide a green compact electrode for discharge surface treatment used for discharge surface treatment for generating discharge between a work and a green compact electrode obtained by pressuring and compacting a metal powder or a powder of a compound metal, and using the discharge energy forming a coating consisting of an electrode material or a substance obtained through a reaction of the electrode material with the discharge energy on the work surface; the electrode is obtained by mixing a bonding agent with the metal powder or the compound metal powder, and pressuring and compacting the mixed powder with a die.
Accordingly, particles of the metal powder or the compound metal powder are bonded to each other by a bonding agent to harden an electrode with powder, which make electric resistance of the electrode lower. With this feature, the electrode strength and electric resistance required as a green compact electrode for discharge surface treatment can be obtained even though the electrode is compacted at a low compacting pressure.
The present invention can provide a green compact electrode for discharge surface treatment in which the bonding agent is a carbon-contained polymer-base bonding agent such as epoxy resin or phenol resin.
Accordingly, in the discharge surface treatment, in addition to reaction of the metal powder or the compound metal powder with the carbon in treatment liquid, the metal powder or the compound metal powder reacts with the carbon in the bonding agent, so that hard carbide metal coating can be obtained.
The present invention can provide a method of manufacturing the green compact electrode for discharge surface treatment used for discharge surface treatment for generating discharge between a work and a green compact electrode obtained by pressuring and compacting the metal powder or a powder of a compound metal, and using the discharge energy forming a coating consisting of an electrode material or a substance obtained through a reaction of the electrode material with the discharge energy on the work surface; the method comprising the steps of mixing a soft metal powder with the metal powder or the compound metal powder, and pressuring and compacting the mixed powder with a die.
Accordingly, when a green compact electrode is pressured and compacted, the soft metal powder enters the inter-particle space of the metal powder or the compound metal powder as a bonding agent and plastically deforms along the inter-particle space to harden the electrode with powder, which makes the electric resistance of the electrode lower. With this feature, the electrode strength and electric resistance required as a green compact electrode for discharge surface treatment can be obtained even though the electrode is compacted at a low compacting pressure.
The present invention can provide a method of manufacturing the green compact electrode for discharge surface treatment in which the compound metal powder is a powder of TiH2, and the soft metal powder is a powder of Ag.
Accordingly, when a green compact electrode is pressured and compacted, the Ag powder which is comparatively soft and has low electric resistance enters the inter-TiH2-particle space and plastically deforms in the inter-particle space to harden the electrode with powder, which makes the electric resistance of the electrode lower. With this feature, the electrode strength and electric resistance required as a green compact electrode for discharge surface treatment can be obtained even though the electrode is compacted at a low compacting pressure. In this green compact electrode, hard anodic oxidation coating of TiC is obtained in the discharge surface treatment due to a reaction of TiH2 with the carbon in the treatment liquid.
The present invention can provide a method of manufacturing the green compact electrode for discharge surface treatment used for discharge surface treatment for generating discharge between a work and a green compact electrode obtained by pressuring and compacting a metal powder or a powder of a compound metal, and using the discharge energy forming a coatings consisting of an electrode material or a substance obtained through a reaction of the electrode material with the discharge energy on the work surface; the method comprises the steps of filling the metal powder or the compound metal powder into a die while vibrating the die, and pressuring and compacting the powder in the die. The case of the vibration filling as described above assumes conditions as follows: several grams to hundreds of grams as a filled amount; tens of seconds as a time for vibration filling; 1-50 xcexcm as a particle diameter; 5 xcexcm or more as an amplitude; and 10 Hz or more as a vibration frequency.
Because of the vibration filling, the metal powder or the compound metal powder is densely filled in the die, and the metal powder or the compound metal powder can uniformly be filled in the die. With this feature, the electrode strength and electric resistance required as a green compact electrode for discharge surface treatment can be obtained even through the electrode is compacted at a low compacting pressure.
The present invention can provide a method of manufacturing the green compact electrode for discharge surface treatment in which ultrasonic vibration is applied to the die.
Because of the ultrasonic vibration filling, the metal powder or the compound metal powder is effectively densely filled in the die, and the metal powder or the compound metal powder can uniformly be filled in the die. With this feature, the electrode strength and electric resistance required as a green compact electrode for discharge surface treatment can be obtained even though the electrode is compacted at a low compacting pressure.
The present invention can provide a method of manufacturing the green compact electrode for discharge surface treatment used for discharge surface treatment for generating discharge between a work and a green compact electrode obtained by pressuring and compacting metal powder or compound metal powder, and by using the discharge energy forming a coating consisting of an electrode material or a substance obtained through reaction of the electrode material with the discharge energy on the work surface; the method comprises the steps of mixing a bonding agent with a metal powder or a compound metal powder, and pressuring and compacting the mixed powder with a die.
Accordingly, the metal powder or compound metal powder is bonded by a bonding agent to harden an electrode with powder, which make electric resistance of the electrode lower. With this feature, the electrode strength and electric resistance required as a green compact electrode for discharge surface treatment can be obtained even though the electrode is compacted at a low-compacting pressure.
The presents invention can provide a method of manufacturing the green compact electrode for discharge surface treatment in which the bonding agent is a carbon-contained polymer-base bonding agent such as epoxy resin and phenol resin.
Accordingly, in the discharge surface treatment, in addition to a reaction of the metal powder or the compound metal powder with the carbon in the treatment liquid, the metal powder or the compound metal powder reacts with the carbon in the bonding agent, so that a hard carbide metal coating can be obtained.